Growing demand for low-cost mobile broadband connectivity is driving the development of heterogeneous cellular networks. It is envisioned that a range of different Radio Access Technologies (RATs) and WiFi may all co-exist. It may be also possible to complement macro cells by a multitude of smaller cells, such as micro, pico and femto cells, where by the cells could use the same RAT on the same and/or different carriers. Such heterogeneous systems will be significantly more complex to manage than today's networks.
One challenge with this development is that signalling needed to manage a connection of the User Equipment (UE) to a specific RAT and/or to a specific cell either in downlink or uplink, requires signalling that may represent a considerable overhead with respect to w.r.t. data payload and latency w.r.t duration of the data session, e.g. in the case of Machine Type Communication (MTC).
Another challenge is caused by increased interference levels in the network by the increased signalling needed and/or increased density of the network due to the small cells deployed to complement the macro cells.